STI is working with multiple oil and gas refineries to perform fenceline monitoring of refinery emissions in advance of a Federal rule that takes effect in November 2017. The fenceline monitoring portion of the rule is intended to ensure that hazardous air pollutant emissions from refineries are controlled, with specific control actions required if fenceline concentrations exceed a specified level. Measurements include 14-day benzene passive samples collected every 2,000 feet around refinery fencelines.